The present invention relates to an anion exchange resin of surface functional type and the process for producing the same.
More particularly, the present invention relates to an anion exchange resin of surface functional type which is used for anion exchange chromatography and the process for producing the same.
Recently, ion exchange chromatography is used widely. For example, environmental analyses of atmosphere and water of rivers or lakes; analyses of ions in blow down water of boiler; maintenance and control of industrial plants such as watch of balance of ion concentration in a plating bath; impurity check of medicinal drugs; and analyses of food additives.
The reason why ion exchange chromatography has been used widely is that inorganic ions can be analyzed rapidly and easily with the use of a conductivity detector.
In order to use a conductivity detector, it is necessary to lower conductance of eluent. That means concentration of eluent is obliged to be low.
In order to separate ions rapidly with low concentration eluent, a packing is required to be a surface functional type.
To satisfy such demands, there have been reported so far the following several production methods of a low capacity anion exchange resin used for anion exchange chromatography, but each has its merits and demerits.
One is a method in which a fine anion exchange resin which diameter is not more than 1 .mu.m is affixed to the surface of a crosslinked polystyrene or the surface sulfonated crosslinked polystyrene which diameter is about 10 .mu.m. Such agglomerated anion exchange resin, however, has trouble in its life time. It also seems difficult to get smaller particles.
Another method is one in which ion exchange group is introduced to a surface of porous silica gel or glass. But in case of using silica gel or glass beads there is a limit of eluent which can be used.
Further, recently a new method has been proposed. That is, after a crosslinked polystyrene is chloromethylated for a short time, it is aminated. Then, an anion exchange resin of surface functional type is obtained. But such resin hasn't had a sufficient separation ability yet. Further, when an anion exchange resin is produced in a large amount in this method, the resin reproducibility with same properties will be difficult.
The present inventors formerly invented an anion exchange resin of surface functional type in which is covalently bonded pendently a polyamine having at least one kind of from primary to tertiary amines and quaternary ammonium group on the surface of a crosslinked copolymer, and an anion exchange group does not exist essentially in the inside of the crosslinked copolymer.
In said resin, however, the thickness of a superficial functional group is not so thin that separation ability in ion exchange chromatography is not sufficient.
The present inventors have accomplished the present invention as a result of extensive study in more detail in view of improving such a demerit.